Question

If 2x^1/3 + 2x^–1/3 = 5, then x is equal to –

• A. 1 or –1
• B. 2 or 1/2
• C. 8 or 1/8
• D. 4 or 1/4

Answer 1

Answer: (C)

8 or 1/8

Answer 2

x^1/3 = t

2t² – 5t + 2 = 0

Ю (2t – 1) (t–2) = 0 Ю t =$1/2$, 2

Ю x^1/3 = $1/2$, 2 Ю x = 1/8, 8